Display apparatus, display control apparatus, and display control method as well as program

ABSTRACT

A display apparatus includes: a plurality of pixel circuits arrayed in a matrix fashion; a light emitting circuit provided to each pixel circuit and emitting light correspondingly to a drive current; and a detection circuit provided to a predetermined pixel circuit and outputting a signal according to a temperature that varies with luminance of the light emitting circuit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display apparatus, a display controlapparatus, and a display control method as well as a program, and moreparticularly, to a display apparatus, a display control apparatus, and adisplay control method as well as a program configured to suppress theoccurrence of burn-in.

2. Description of Related Art

Recently, an organic EL (Electro Luminescence) display using organic ELelements receives increasing interest as a type of FPD (Flat PanelDisplay), and the organic EL display has been under active development.

The current mainstream of FPDs is an LCD (Liquid Crystal Display). TheLCD, however, is not a device that uses self-luminescent elements andhas to use illumination members, such as a backlight and a polarizationplate. The LCD therefore has problems, such as an increase of the devicein thickness and insufficient luminance. By contrast, the organic ELdisplay is a device that uses self-luminescence elements. The organic ELluminescence display is therefore advantageous over the LCD in that itcan be thinner because a backlight or the like is unnecessary inprinciple and it can achieve high luminance.

In particular, a so-called active matrix organic EL display providedwith a TFT circuit that performs switching in each pixel is able tohold-light ON each pixel and power consumption can be suppressed due tothis ability. In addition, because the active matrix organic EL displaycan be increased in screen size and achieve higher definition withrelative ease, active developments have been made and it is expected tobecome the mainstream of the next-generation FPD.

Incidentally, the characteristic of the organic EL elements varies ordeteriorates with the ambient temperature or self-heating. Also, whenvideos are displayed, the temperature environment of the organic ELelements varies from one video to another. Deterioration conditions ofthe organic EL elements therefore may differ among portions within thepanel. For example, in a case where the organic EL display is used asthe display portion of a TV set, when reception channel information (anumber indicating the reception channel) is kept displayed on the screencorner, the organic EL elements in the portion where the receptionchannel information is kept displayed deteriorate faster, and aso-called burn-in phenomenon occurs.

The burn-in phenomenon will now be described, for example, withreference to FIG. 1.

FIG. 1 shows a screen 11A in a state where the reception channelinformation is displayed and a screen 11B in a state where burn-inoccurs.

For example, as is shown in FIG. 1, “12” is displayed on the upper rightcorner of the screen 11A as the reception channel information. When thereception channel information is kept displayed at the same position fora long time, burn-in occurs because the organic EL elements in thisportion deteriorate. As is shown in the screen 11B in a state whereburn-in occurs, when a bright video is displayed, burn-in appearing asdark “12” occurs in the portion where the reception channel informationhas been displayed (within a region encircled by a broken line in FIG.1).

As a technique of mitigating or preventing such a burn-in phenomenon,for example, JP-A-11-26055 discloses a technique of displaying a videoto be kept displayed fixedly by inverting the video at predeterminedperiods, or a technique of displaying such a video by shifting the videoat predetermined periods. In a case where the video is displayed whilebeing inverted at predetermined periods, the technique is effective fora monochrome display. However, for a color display, the inverted videobecomes a totally different video. It is therefore difficult to adoptthis technique to a color display. In a case where a video is displayedby shifting the video at predetermined periods, the display position isdisplaced. It is therefore unsuitable to adopt this technique when astill image is displayed.

In addition, for example, JP-A-2002-351403 discloses a method ofextending the life by providing dummy pixels outside the display regionto detect terminal voltages of the organic EL elements in the dummypixels when they emits light as a degree of deterioration of the dummypixels, and correcting a video signal on the basis of the detectionresult. However, with a correction on the basis of the detection resultof the terminal voltages of the dummy pixels, merely the entire displayregion is corrected from the detection result and the organic ELelements within the display region are not corrected locally. It istherefore difficult to prevent burn-in that occurs locally with thismethod.

Also, JP-A-2006-201784 discloses a method of correcting a temperature byfeeding back an output from a build-in temperature sensor by providingthe temperature sensor on the periphery of the panel. However, in a casewhere the temperature sensor on the periphery of the panel is used, itis possible to detect the overall temperature, but it is quite difficultto accurately detect the temperature distribution within a displayregion where heat is chiefly generated. It is therefore difficult toprevent burn-in that occurs locally.

SUMMARY OF THE INVENTION

As has been described above, it has been difficult to suppress burn-inthat occurs locally with the method of preventing the burn-in phenomenonin the related art.

It is therefore desirable to make it possible to suppress the occurrenceof burn-in.

According to an embodiment of the present invention, there is provided adisplay apparatus including: a plurality of pixel circuits arrayed in amatrix fashion; a light emitting circuit provided to each pixel circuitand emitting light correspondingly to a drive current; and a detectioncircuit provided to a predetermined pixel circuit and outputting asignal according to a temperature that varies with luminance of thelight emitting circuit.

According to another embodiment of the present invention, there isprovided a display control apparatus having: display means including aplurality of pixel circuits arrayed in a matrix fashion, a lightemitting circuit provided to each pixel circuit and emitting lightcorrespondingly to a drive current, and a detection circuit provided toa predetermined pixel circuit and outputting a signal according to atemperature that varies with luminance of the light emitting circuit;temperature calculation means for calculating the temperature on thebasis of the signal outputted from the detection circuit; and correctionmeans for correcting the drive current supplied to the light emittingcircuit on the basis of the temperature calculated by the temperaturecalculation means.

According to another embodiment of the present invention, there isprovided a display control method of a display control apparatus thatcontrols a display of a video and includes a plurality of pixel circuitsarrayed in a matrix fashion, a light emitting circuit provided to eachpixel circuit and emitting light correspondingly to a drive current, anda detection circuit provided to a predetermined pixel circuit andoutputting a signal according to a temperature that varies withluminance of the light emitting circuit, including the steps of:calculating the temperature on the basis of the signal outputted fromthe detection circuit; and correcting the drive current supplied to thelight emitting circuit on the basis of the calculated temperature.

According to another embodiment of the present invention, there isprovided a program causing a computer to function as a display controlapparatus that controls a display of a video and includes a plurality ofpixel circuits arrayed in a matrix fashion, a light emitting circuitprovided to each pixel circuit and emitting light correspondingly to adrive current, and a detection circuit provided to a predetermined pixelcircuit and outputting a signal according to a temperature that varieswith luminance of the light emitting circuit, and the program causes thecomputer to function as follows: temperature calculation means forcalculating the temperature on the basis of the signal outputted fromthe detection circuit; and correction means for correcting the drivecurrent supplied to the light emitting circuit on the basis of thetemperature calculated by the temperature calculation means.

According to the embodiment of the present invention, the light emittingcircuit provided to each of a plurality of pixel circuits arrayed in amatrix fashion emits light correspondingly to a drive current. Thedetection circuit provided to a predetermined pixel circuit outputs asignal according to a temperature that varies with luminance of thelight emitting circuit.

According to the embodiment of the present invention, the displaycontrol apparatus includes a plurality of pixel circuits arrayed in amatrix fashion, a light emitting circuit provided to each pixel circuitand emitting light correspondingly to a drive current, and a detectioncircuit provided to a predetermined pixel circuit and outputting asignal according to a temperature that varies with luminance of thelight emitting circuit. The temperature is calculated on the basis ofthe signal outputted from the detection circuit and the drive currentsupplied to the light emitting circuit is corrected on the basis of thecalculated temperature.

According to the embodiments of the present invention, it is possible tosuppress the occurrence of burn-in.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view used to describe a burn-in phenomenon;

FIG. 2 is a block diagram showing an example of the configuration of adisplay apparatus according to an embodiment of the present invention;

FIG. 3 is a circuit diagram of a pixel circuit corresponding to onepixel forming a display panel;

FIG. 4 is a view used to describe the timing of an operation to read outthe voltage at a node of a temperature detection circuit;

FIG. 5 is a view used to describe the temperature characteristic of aPIN diode when driven by forward bias;

FIG. 6 is a view used to describe the temperature dependencycharacteristic of the PIN diode;

FIG. 7 is a flowchart used to describe the processing by the displayapparatus to find a correction coefficient on the basis of temperaturedata on a pixel-by-pixel basis, correct an image, and display thecorrected image; and

FIG. 8 is a circuit diagram of the pixel circuit according to anembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a concrete embodiment of the present invention will bedescribed in detail with reference to the drawings.

FIG. 2 is a block diagram showing an example of the configuration of adisplay apparatus according to an embodiment of the present invention.

Referring to FIG. 2, a display apparatus 21 includes a timing generationcircuit 22, a scan circuit 23, a video signal drive circuit 24, adisplay panel 25, a temperature signal processing circuit 26, a memorycircuit 27, and an arithmetic circuit 28.

A synchronization signal at a predetermined frequency specifying thebreak of a video signal is supplied to the timing generation circuit 22from an unillustrated circuit in the preceding stage. According to thissynchronizing signal, the timing generation circuit 22 generates timingsignals each determining the timing of processing in the scan circuit23, the video signal drive circuit 24, and the temperature signalprocessing circuit 26 and supplies the timing signals to the scancircuit 23, the video signal drive circuit 24, and the temperaturesignal processing circuit 26.

The scan circuit 23 performs the control to scan pixels, which areprovided to the display panel 25 in a matrix fashion, line by lineaccording to the timing signal (for example, a vertical synchronizingsignal) supplied from the timing generation circuit 22.

The video signal drive circuit 24 drives the respective pixels of thedisplay panel 25 on the basis of a video signal supplied via thearithmetic circuit 28 according to the timing signal (for example, ahorizontal synchronizing signal) supplied from the timing generationcircuit 22.

The display panel 25 has pixels formed of organic EL elements andprovided in a matrix fashion and displays a video according to signalssupplied from the scan circuit 23 and the video signal drive circuit 24.Also, as will be described below with reference to FIG. 3, each of thepixels of the display panel 25 is provided with a temperature detectioncircuit. The display panel 25 supplies a signal outputted from thetemperature detection circuit of each pixel (for example, a signalindicating potential at a node A of FIG. 3 described below) to thetemperature signal processing circuit 26.

As will be described below with reference to FIG. 6, a preliminarilyfound equation that linearly approximates measurement values of theabsolute temperature T and an anode potential difference ΔV is set inthe temperature signal processing circuit 26. Signals from thetemperature detection circuits of the respective pixels of the displaypanel 25 are supplied to the temperature signal processing circuit 26.The temperature signal processing circuit 26 finds the anode potentialdifference ΔV from these signals and calculates the absolute temperatureT of each pixel from the anode potential difference ΔV. The temperaturesignal processing circuit 26 then converts the absolute temperature T ofeach pixel from the analog form to the digital form and makes the memorycircuit 27 store the resulting temperature data on a pixel-by-pixelbasis.

The memory circuit 27 stores the temperature data supplied from thetemperature signal processing circuit 26 on a pixel-by-pixel basis. Forexample, the memory circuit 27 is able to store temperature data for oneframe of a video signal. Besides the temperature data, the memorycircuit 27 stores data necessary for the processing by the arithmeticcircuit 28, for example, one frame of a video signal and correctioncoefficients used to correct the video signal.

A video signal is supplied to the arithmetic circuit 28 from anunillustrated circuit in the preceding stage. The arithmetic circuit 28supplies one frame of a video signal to the memory circuit 27 so thatthe video signal is temporarily stored therein. Also, upon supply of oneframe of a video signal, the arithmetic circuit 28 reads out the videosignal of the last frame immediately preceding the current frame and thetemperature data found when the video on the basis of the video signalof the last frame was displayed on the display panel 25, both of whichare stored in the memory circuit 27. The arithmetic circuit 28 thenfinds the correction coefficient used to correct the video signal levelof the current frame on a pixel-by-pixel basis and makes the memorycircuit 27 temporarily store the correction coefficients.

For example, in a case where the video signal level (luminance value) ofthe last frame is large and the temperature data when the video on thebasis of the video signal of the last frame was displayed indicates ahigh temperature, the arithmetic circuit 28 finds a correctioncoefficient such that lowers the video signal level of the current frameon a pixel-by-pixel basis. For example, the arithmetic circuit 28 has atable of correction coefficients in which the video signal level and thetemperature data are correlated with each other, and it finds thecorrection coefficient by referring to the table.

The arithmetic circuit 28 then corrects the video signal level of thecurrent frame by multiplying the video signal level of the current frameby the correction coefficient stored in the memory circuit 27 on apixel-by-pixel basis, and supplies the corrected video signal to thevideo signal drive circuit 24.

As has been described, in the display apparatus 21, the video signal iscorrected on the basis of temperature data of the pixels forming thedisplay panel 25 found on a pixel-by-pixel basis and a video on thebasis of the corrected video signal is displayed on the display panel25.

FIG. 3 is a circuit diagram of a pixel circuit corresponding to onepixel forming the display panel 25.

Referring to FIG. 3, a pixel circuit 31 includes a light emittingcircuit 32 and a temperature detection circuit 33.

The light emitting circuit 32 of the pixel circuit 31 is connected tothe scan circuit 23 of FIG. 2 via a scan line (WS) 34 and a power supplyline (DS) 35 and connected to the video signal drive circuit 24 of FIG.2 via a pixel signal line (SIG) 36. Also, the temperature detectioncircuit 33 of the pixel circuit 31 is connected to the scan circuit 23via a read line (READ) 37 and connected to the temperature signalprocessing circuit 26 of FIG. 2 via a current signal line (ISIG) 38 anda temperature detection signal line (SIGT) 39.

The light emitting circuit 32 has a write transistor (WSTFT) 41, a drivetransistor (DSTFT) 42, a storage capacitor (CS) 43, and an organic ELelement 44.

The gate of the write transistor 41 is connected to the scan line 34 andthe drain of the write transistor 41 is connected to the pixel signalline 36. The source of the write transistor 41 is connected to the gateof the drive transistor 42, and one end of the storage capacitor 43 isconnected to this connection point.

The drain of the drive transistor 42 is connected to the power supplyline 35 and the source of the drive transistor 42 is connected to theanode of the organic EL element 44. Also, the other end of the storagecapacitor 43 is connected to this connection point. Also, the cathode ofthe organic EL element 44 is connected to predetermined cathodepotential (CATHODE).

In the light emitting circuit 32 configured as above, charges accordingto the pixel signal supplied via the pixel signal line 36 areaccumulated and held in the storage capacitor 43 at the timing of thecontrol signal supplied via the scan line 34, and a currentcorresponding to the charges flows to the organic EL element 44. Theorganic EL element 44 thus emits light at luminance corresponding to thepixel signal. The temperature of the organic EL element 44 varies withthe luminance thereof.

The temperature detection circuit 33 includes transistors (TFTs) 51 and52 and a PIN diode (p-intrinsic-n Diode) 53.

The gate of the transistor 51 is connected to the read line 37, thedrain of the transistor 51 is connected to the current signal line 38,and the source of the transistor 51 is connected to the anode of the PINdiode 53. Hereinafter, this connection point is referred to as the nodeA where appropriate and the drain of the transistor 52 is connected tothe node A. Also, the gate of the transistor 52 is connected to the readline 37 and the source of the transistor 52 is connected to thetemperature detection signal line 39. The cathode of the PIN diode 53 isconnected, for example, to predetermined reference potential (COM).

In the temperature detection circuit 33 configured as above, each timethe display panel 25 displays one frame of a video, that is, each timethe organic EL element 44 emits light according to the pixel signal inthe light emitting circuit 32, processing to read out potential at thenode A twice from the temperature detection circuit 33 is performed.

More specifically, timing of an operation to read out the voltage at thenode A in the temperature detection circuit 33 will be described withreference to FIG. 4.

FIG. 4 shows potential of a read signal supplied to the transistors 51and 52 via the read line 37, a current value of the current flowing tothe PIN diode 53 via the current signal line 38, and potential at thenode A.

Initially, a current value IF1 is outputted to the current signal line38 from the temperature signal processing circuit 26. The transistors 51and 52 come ON as the potential of the read signal is switched from lowpotential to high potential at the timing at which reading of thepotential at the node A for the first time is started. As the transistor51 comes ON, a constant current at the current value IF1 is supplied tothe PIN diode 53 via the current signal line 38. The potential at thenode A thus becomes V1. At the same time, as the transistor 51 comes ON,the potential V1 at the node A is outputted to the temperature detectionsignal line 39. The potential of the read signal is then switched fromhigh potential to low potential.

After an elapse of a predetermined time since the current outputted tothe current signal line 38 from the temperature signal processingcircuit 26 dropped from the current value IF1 to a current value IF2,the potential of the read signal is switched from low potential to highpotential at the timing at which reading of the potential at the node Afor the second time is started. The transistors 51 and 52 thus come ONand a constant current at the current value IF2 is supplied to the PINdiode 53. Accordingly, the potential at the node A becomes V2 and thepotential V2 at the node A is outputted via the temperature detectionsignal line 39. The potential of the read signal is then switched fromhigh potential to low potential.

As has been described, the temperature detection circuit 33 outputs tothe temperature signal processing circuit 26 both the anode potential V1of the PIN diode 53 when a constant current at the current value IF1flows to the PIN diode 53 and the anode potential V2 of the PIN diode 53when a constant current at the current value IF2 flows to the PIN diode53. The temperature signal processing circuit 26 then calculates theabsolute temperature from a potential difference between the anodepotential V1 and the anode potential V2 on the basis of the temperaturecharacteristic of the PIN diode 53.

The temperature characteristic of the PIN diode 53 when driven byforward bias will now be described with reference to FIG. 5.

In FIG. 5, the abscissa is used for a voltage between the anode and thecathode of the PIN diode 53 and the ordinate is used for the forwardcurrent flowing in the forward direction from the anode of the PIN diode53. It should be noted that the temperature detection circuit 33 of FIG.3 outputs the anode potential of the PIN diode 53 with respect to thepredetermined reference potential but the anode potential with respectto the cathode potential of the PIN diode 53, that is, the voltagebetween the anode and the cathode, will be described with reference toFIG. 5.

For example, the temperature dependency of the anode potentialdifference ΔV between the voltage V1 when the forward current IF1 isflown in the forward direction from the anode of the PIN diode 53 andthe voltage V2 when the forward current IF2 (IF1>IF2) is flown isexpressed as Equation (1).

$\begin{matrix}{{\Delta\; V} = {\eta\frac{k \cdot T}{q}{\ln( \frac{{IF}\; 1}{{IF}\; 2} )}}} & (1)\end{matrix}$

In Equation (1) above, η is a coefficient in the fabrication process, kis a Boltzmann coefficient, T is the absolute temperature, and q is acharge amount of one electron.

Hence, by obtaining the anode potential difference ΔV (V1−V2) and theforward currents IF1 and IF2, the temperature signal processing circuit26 of FIG. 2 becomes able to find the absolute temperature T of the PINdiode 53 by calculating Equation (1) above.

FIG. 6 is a view showing the temperature dependency characteristic ofthe PIN diode 53.

In FIG. 6, the abscissa is used for the anode potential difference ΔVand the ordinate is used for the absolute temperature T. FIG. 6 showsthe anode potential difference ΔV measured when 100 μA and 1 μA wereflown as the forward currents IF1 and IF2, respectively, and theabsolute temperature T measured in this instance.

As is shown in FIG. 6, the anode potential difference ΔV varies linearlywith respect to the absolute temperature T and an equation shown in FIG.6 is found through linear approximation. For example, the linearapproximation equation found in this manner can be set in thetemperature signal processing circuit 26 of FIG. 2. Accordingly, thesignal processing circuit 26 reads out the anode potentials V1 and V2when the forward currents IF1 and IF2 were respectively flown to the PINdiode 53 to find the temperature of each pixel by calculating the anodepotential difference ΔV, and makes the memory circuit 27 store thetemperature data.

As has been described, in the display apparatus 21, by providing thetemperature detection circuit 33 to each pixel circuit 31, it becomespossible to detect the temperature of each pixel. The arithmetic circuit28 reads out the temperature data thus stored in the memory circuit 27to find the correction coefficient and corrects the video signal.

FIG. 7 is a flowchart used to describe the processing by the displayapparatus 21 of FIG. 2 to find the correction coefficient on the basisof the temperature data on a pixel-by-pixel basis, correct a video, anddisplay the corrected video. For example, this processing is performedeach time one frame of a video signal is supplied to the arithmeticcircuit 28 from the circuit in the preceding stage. While the processingis performed on one certain frame, the video signal of the last frameimmediately preceding this frame is stored in the memory circuit 27.

In Step S11, the arithmetic circuit 28 receives one frame of a videosignal supplied from the circuit in the preceding circuit and the flowproceeds to the processing in Step S12.

In Step S12, the temperature signal processing circuit 26 reads out thepotentials V1 and V2 at the node A from the temperature detectioncircuit 33 for each pixel circuit 31 of FIG. 3, and the flow proceeds tothe processing in Step S13. Herein, the potentials V1 and V2 at the nodeA when the video of the last frame was displayed are read out from thetemperature detection circuit 33.

In Step S13, the temperature signal processing circuit 26 calculates theabsolute temperature T of the PIN diode 53 from the potentials V1 and V2at the node A on the basis of the temperature characteristic of the PINdiode 53. The temperature signal processing circuit 26 converts theabsolute temperature T, which is found on a pixel-by-pixel basis, thatis, for each pixel circuit 31, from the analog form to the digital formand makes the memory circuit 27 store the resulting temperature data.

After the processing in Step S13, the flow proceeds to the processing inStep S14, where the arithmetic circuit 28 reads out the video signal ofthe last frame stored in the memory circuit 27 and the temperature dataof each pixel stored in Step S13 from the memory circuit 27. Thearithmetic circuit 28 then finds the correction coefficient on apixel-by-pixel basis on the basis of the video signal and thetemperature data and makes the memory circuit 27 store the correctioncoefficients. The flow then proceeds to the processing in Step S15.

In Step S15, the arithmetic circuit 28 reads out the correctioncoefficient stored in the memory circuit 27 in Step S14 on apixel-by-pixel basis and corrects the video signal on a pixel-by-pixelbasis by multiplying the correction coefficient by the pixel valuecorresponding to the pixel of interest and contained in the video signalreceived in Step S11.

After the processing in Step S15, the flow proceeds to the processing inStep S16, where the arithmetic circuit 28 supplies the corrected videosignal to the video signal drive circuit 24 to make the display panel 25display the video. Also, the arithmetic circuit 28 rewrites (updates)the video signal of the last frame stored in the memory circuit 27 withthe current video signal and the processing terminates.

As has been described, in the display apparatus 21, the temperaturesignal processing circuit 26 calculates the temperature of each pixel ofthe display panel 25 and the arithmetic circuit 28 finds the correctioncoefficient used to correct the video signal on the basis of thecalculated temperature and corrects the video signal. Hence, forexample, when the temperature of a given pixel is high, it becomespossible to make a correction in such manner that the luminance value ofthe video signal corresponding to this pixel is reduced, that is, tocorrect the video signal on a pixel-by-pixel basis. By correcting thevideo signal through the temperature feedback as described above, thatis, by correcting a current to be supplied to the organic EL element 44in the light emitting circuit 32, it becomes possible to avoid an eventthat the temperature of the display panel 25 rises locally, which canconsequently suppress the occurrence of burn-in. It thus becomespossible to avoid deterioration of the image quality caused by burn-in.Accordingly, the life of the display panel 25 can be prolonged.

In particular, as has been described with reference to FIG. 1, when thereception channel information or the like is kept displayed, it isthought that burn-in occurs because the organic EL elements deterioratewith the rising of the temperature in the corresponding portion. Toeliminate this problem, the display apparatus 21 is able to adjust theluminance of the portion where the reception channel information isdisplayed on a pixel-by-pixel basis in response to the temperature. Itthus becomes possible to suppress local deterioration of the organic ELelements.

In the pixel circuit 31, by forming the temperature detection circuit 33from the PIN diode 53, the temperature detection circuit 33 can befabricated in the process of fabricating the light emitting circuit 32.It thus becomes possible to fabricate the temperature detection circuit33 with east at a low cost without any change from the process in therelated art.

Also, as is shown in FIG. 3, by providing the PIN diode 53 at theposition in the vicinity of the light emitting circuit 32, inparticular, in the vicinity of the organic EL element 44 in thetemperature detection circuit 33, it becomes possible to detect avariance in temperature of the light emitting circuit 32 more accuratelyby the PIN diode 53.

Also, because the temperature detection circuit 33 detects the anodepotential of the PIN diode 53, it can be achieved by a simple circuitconfiguration formed of two transistors 51 and 52.

Besides finding the pixel temperature from the anode potential of thePIN diode 53, the temperature signal processing circuit 26 may find, forexample, the temperature of the pixel from the voltage between the anodeand the cathode of the PIN diode 53. In this case, a transistor to readout the potential at the cathode of the PIN diode 53 is provided in thepixel circuit 31.

More specifically, FIG. 8 shows the circuit diagram of the pixel circuitin such a case according to an embodiment of the present invention.

In the drawing, like members are labeled with like reference numeralswith respect to FIG. 3 and descriptions of such members are omitted inthe following where appropriate.

To be more specific, referring to FIG. 8, the light emitting circuit 32is common with the counterpart of FIG. 3 in that it includes the writetransistor 41, the drive transistor 42, the storage capacitor 43, andthe organic EL element 44 and the temperature detection circuit 33 iscommon with the counterpart of FIG. 3 in that it includes thetransistors 51 and 52 and the PIN diode 53. The both circuits are alsocommon with the respective counterparts of FIG. 3 in that they areconnected to the scan circuit 23 via the scan line 34, the power supplyline 35, and the read line 37, connected to the video signal drivecircuit 24 via the pixel signal line 36, and connected to thetemperature signal processing circuit 26 via the current signal line 38and the temperature detection signal line 39.

A temperature detection circuit 33′ of FIG. 8 is different from thecounterpart of FIG. 3 in that a transistor 61 is newly provided and itis connected to the temperature signal processing circuit 26 via atemperature detection signal line (SIGC) 62.

In the temperature detection circuit 33′ of a pixel circuit 31′ of FIG.8, the gate of the transistor 61 is connected to the read line 37, thedrain of the transistor 61 is connected to the cathode of the PIN diode53, and the source of the transistor 61 is connected to the temperaturedetection signal 62. The transistor 61 comes ON simultaneously with thetransistor 52 and supplies the cathode potential of the PIN diode 53 tothe temperature signal processing circuit 26 via the temperaturedetection signal line 62.

The anode potential of the PIN diode 53 is supplied to the temperaturesignal processing circuit 26 via the temperature detection signal 39 andthe cathode potential of the PIN diode 53 is also supplied to thetemperature signal processing circuit 26 via the temperature detectionsignal line 62. The temperature signal processing circuit 26 thencalculates the temperature of the PIN diode 53 on the basis of thevoltage between the anode and the cathode of the PIN diode 53.

As has been described, by calculating the temperature using the voltagebetween the anode and the cathode of the PIN diode 53, it becomespossible to calculate the temperature of the PIN diode 53 moreaccurately than in a case where the anode potential is used.

In this embodiment, the temperature detection circuit 33 detects thetemperature each time the light emitting circuit 32 emits lightaccording to one frame of a video signal. The light emitting circuit 32and the temperature detection circuit 33, however, may be controlledindependently. More specifically, for example, it may be configured insuch a manner that the temperature detection circuit 33 detects thetemperature once while the light emitting circuit 32 emits apredetermined number of rays of light according to a predeterminednumber of frames. By extending the interval at which the temperature isdetected by the temperature detection circuit 33 in this manner, aburden of the processing on the arithmetic circuit 28 can be lessened.

Also, in this embodiment, the temperature detection circuit 33 isprovided to each pixel circuit 31 of the display panel 25. However, itmay be configured in such a manner that the pixel circuit 31 is providedto each pixel made of RGB or the display panel 25 is divided into aplurality of regions to provide the pixel circuit 31 to each region. Byreducing the number of the temperature detection circuits 33 in thismanner, the number of items of temperature data to be detected can bereduced, which makes it possible to make the memory circuit 27 smallerand to accelerate the processing.

Alternatively, it may be configured in such a manner that thetemperature detection circuit 33 is provided to all the pixel circuits31, so that the temperature data is detected from each predeterminednumber of pixel circuits 31 by adjusting the temperature detectioncircuits 33 to be sampled.

Also, as is shown in FIG. 3, the light emitting circuit 32 adopts a 2Tr(transistor)+1C (capacitor) circuit. The light emitting circuit 32,however, can adopt any type of circuit.

Each processing described with reference to the flowchart above is notnecessarily carried out time sequentially in order of description of theflowchart, and it includes processing to be carried out in parallel orseparately (for example, the parallel processing or processing by anobject). Also, the program for the arithmetic circuit 28 to perform theprocessing includes programs other than a program pre-stored in thearithmetic circuit 28. For example, a program may be newly stored (theprogram may be updated) in the arithmetic circuit 28 via anunillustrated communication portion.

It should be appreciated that the present invention is not limited tothe embodiments described above and can be modified in various mannerswithout deviating from the scope of the invention.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2008-211719 filedin the Japan Patent Office on Aug. 20, 2008, the entire contents ofwhich is hereby incorporated by reference.

1. A display apparatus comprising: a plurality of pixel circuits arrayedin a matrix fashion; a light emitting circuit provided for each pixelcircuit and configured to emit light according to a drive current; and adetection circuit provided for a predetermined pixel circuit andconfigured to output a signal according to a temperature that varieswith luminance of the light emitting circuit, wherein, the detectioncircuit includes a PIN (p-intrinsic-n) diode and at least two switches,and one terminal of each switch is directly connected to an anode of thePIN diode, and wherein the detection circuit, when a constant current isflown between the anode and a cathode of the PIN diode by driving thePIN diode by forward bias, outputs potential at the anode as the signal.2. The display apparatus according to claim 1, wherein the detectioncircuit, when a constant current is flown between the anode and acathode of the PIN diode by driving the PIN diode by forward bias,outputs a potential difference between potential at the anode andpotential at the cathode as the signal.
 3. The display apparatusaccording to claim 1 or 2, wherein the at least two switches are used tocontrol a current supplied to the PIN diode.
 4. The display apparatusaccording to claim 1 or 2, wherein the PIN diode of the detectioncircuit is at a position adjacent to the light emitting circuit.
 5. Adisplay control apparatus comprising: display means including (a) aplurality of pixel circuits arrayed in a matrix, (b) a light emittingcircuit provided for each pixel circuit and configured to emit lightaccording to a drive current, and (c) a detection circuit provided for apredetermined pixel circuit and configured to output a signal accordingto a temperature that varies with luminance of the light emittingcircuit; temperature calculation means for calculating the temperatureon the basis of the signal outputted from the detection circuit; andcorrection means for correcting the drive current supplied to the lightemitting circuit on the basis of the temperature calculated by thetemperature calculation means, wherein, the detection circuit includes aPIN (p-intrinsic-n) diode and at least two switches, and one terminal ofeach switch is directly connected to an anode of the PIN diode, andwherein the detection circuit, when a constant current is flown betweenthe anode and a cathode of the PIN diode by driving the PIN diode byforward bias, outputs potential at the anode as the signal.
 6. A displaycontrol method of a display control apparatus that controls a display ofa video and includes display means including (a) a plurality of pixelcircuits arrayed in a matrix, (b) a light emitting circuit provided foreach pixel circuit and configured to emit light according to a drivecurrent, and (c) a detection circuit provided for a predetermined pixelcircuit and configured to output a signal according to a temperaturethat varies with luminance of the light emitting circuit, comprising thesteps of: calculating the temperature on the basis of the signaloutputted from the detection circuit; and correcting the drive currentsupplied to the light emitting circuit on the basis of the calculatedtemperature, wherein, the detection circuit includes a PIN(p-intrinsic-n) diode and at least two switches, and one terminal ofeach switch is directly connected to an anode of the PIN diode, andwherein the detection circuit, when a constant current is flown betweenthe anode and a cathode of the PIN diode by driving the PIN diode byforward bias, outputs potential at the anode as the signal.
 7. Anon-transitory computer-readable medium having instructions recordedthereon, wherein the instructions, when read by a computer, cause thecomputer to function as a display control apparatus that controls adisplay of a video and includes (a) a plurality of pixel circuitsarrayed in a matrix, (b) a light emitting circuit provided for eachpixel circuit and configured to emit light according to a drive current,and (c) a detection circuit provided for a predetermined pixel circuitand configured to output a signal according to a temperature that varieswith luminance of the light emitting circuit, wherein the instructionscause the computer to function as follows: calculating the temperatureon the basis of the signal outputted from the detection circuit; andcorrection means for correcting the drive current supplied to the lightemitting circuit on the basis of the temperature calculated by thetemperature calculation means, wherein, the detection circuit includes aPIN (p-intrinsic-n) diode and at least two switches, and one terminal ofeach switch is directly connected to an anode of the PIN diode, andwherein the detection circuit, when a constant current is flown betweenthe anode and a cathode of the PIN diode by driving the PIN diode byforward bias, outputs potential at the anode as the signal.
 8. A displaycontrol apparatus comprising: a display unit including (a) a pluralityof pixel circuits arrayed in a matrix, (b) a light emitting circuitprovided for each pixel circuit and configured to emit light accordingto a drive current, and (c) a detection circuit provided for apredetermined pixel circuit and configured to output a signal accordingto a temperature that varies with luminance of the light emittingcircuit; a temperature calculation unit configured to calculate thetemperature on the basis of the signal outputted from the detectioncircuit; and a correction unit configured to correct the drive currentsupplied to the light emitting circuit on the basis of the temperaturecalculated by the temperature calculation unit, wherein, the detectioncircuit includes a PIN (p-intrinsic-n) diode and at least two switches,and one terminal of each switch is directly connected to an anode of thePIN diode, and wherein the detection circuit, when a constant current isflown between the anode and a cathode of the PIN diode by driving thePIN diode by forward bias, outputs potential at the anode as the signal.